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National Boards => General Highway Talk => Traffic Control => Topic started by: Alps on December 15, 2009, 11:43:10 PM

Title: LED traffic signals
Post by: Alps on December 15, 2009, 11:43:10 PM
This thread can evolve with news, ideas, discussions... starting off with some news

http://news.yahoo.com/s/ap/20091216/ap_on_re_us/us_snow_covered_stoplights
Title: Re: LED traffic signals
Post by: Hellfighter on December 15, 2009, 11:47:22 PM
It'll be interesting to see how that plays out here in Michigan, where we're transitioning to LED Traffic Lights.
Title: Re: LED traffic signals
Post by: agentsteel53 on December 15, 2009, 11:51:52 PM
little wiper blades?  Install in center of light and allow to rotate freely to clear snow before it sticks. 
Title: Re: LED traffic signals
Post by: mightyace on December 15, 2009, 11:52:09 PM
Quote from: AlpsROADS on December 15, 2009, 11:43:10 PM
Energy-efficient traffic lights can't melt snow
http://news.yahoo.com/s/ap/20091216/ap_on_re_us/us_snow_covered_stoplights

Yeah, let's save some electricity.  Who cares if a few more people die in traffic accidents, they're far too many of them anyway.
Title: Re: LED traffic signals
Post by: rawmustard on December 16, 2009, 03:21:05 AM
Quote from: AlpsROADS on December 15, 2009, 11:43:10 PM
This thread can evolve with news, ideas, discussions... starting off with some news

http://news.yahoo.com/s/ap/20091216/ap_on_re_us/us_snow_covered_stoplights

I know this was the subject of a Car Talk puzzler several years ago. Always interesting to see how the media reacts to a problem that really isn't new. Short of using cutaway visors (so there's less surface area for snow to stick), there really isn't a practical solution.
Title: Re: LED traffic signals
Post by: Chris on December 16, 2009, 05:27:45 AM
LED traffic signals consume less energy. That's problematic in snowy states, as traffic signals become invisible due to snow sticking to it and doesn't melt. We had a major problem here a year ago when nearly all traffic signals were invisible during snowfall. It was the rush hour from hell.

Maybe they need to install some heating device that only works during winter. That way you still save energy 9 months a year, but you keep the signals visible for the other 3 months. I don't think installing wiper blades is really an answer, way too maintenance sensitive. Have crews driving all over town cleaning traffic signals isn't very efficient either.
Title: Re: LED traffic signals
Post by: agentsteel53 on December 16, 2009, 05:29:38 AM
is there a way to make the snow not stick?  it seems it's the upper surface of the hood that is the problem, and the snow is resting against the glass, not actually sticking to that.  How would glare be affected if the top quadrant of the hood (say, from 10 o'clock to 2 o'clock, plus or minus an "hour" each way) were eliminated?
Title: Re: LED traffic signals
Post by: Chris on December 16, 2009, 05:34:38 AM
We have them without the hoods. The problem remains if the snow is falling in combination with wind. It just sticks to it like it sticks to traffic signs or directional signage.

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.verkeersnet.nl%2Fwp-content%2Fuploads%2F2009%2F01%2Fled.jpg&hash=3ffc9d00dbdff41398f6fd89892c38d9c378eb6b)
Title: Re: LED traffic signals
Post by: wytout on December 16, 2009, 06:10:09 AM
I guess our snow isn't cold enough in CT.  Most state and local roads here have been transitioning to LED's for 10 years now, and they are the predominant luminary found in most traffic lights.  Even in the worst snows, wind and cold we've had, I don't think I've ever seen one being blocked by crusted snow.
Title: Re: LED traffic signals
Post by: Duke87 on December 16, 2009, 04:21:59 PM
Quote from: wytout on December 16, 2009, 06:10:09 AM
I guess our snow isn't cold enough in CT.  Most state and local roads here have been transitioning to LED's for 10 years now, and they are the predominant luminary found in most traffic lights.  Even in the worst snows, wind and cold we've had, I don't think I've ever seen one being blocked by crusted snow.

I think it's less a matter of temperature and more a matter of the nature and severity of the storm. Consider the locations where this problem has developed: Milwaukee, Oswego, Green Bay, Saint Paul, Des Moines.... these are places that get more and larger snow storms than Connecticut (lake effect, prairie winters...).
Title: Re: LED traffic signals
Post by: wytout on December 17, 2009, 08:06:36 AM
Quote from: agentsteel53 on December 16, 2009, 05:29:38 AM
is there a way to make the snow not stick?  it seems it's the upper surface of the hood that is the problem, and the snow is resting against the glass, not actually sticking to that.  How would glare be affected if the top quadrant of the hood (say, from 10 o'clock to 2 o'clock, plus or minus an "hour" each way) were eliminated?

LED's seem bright enough even in direct sunlight, that maybe the visors could simply be eliminated altogether.  Unlike the old incandescent/lens lamps, there is almost never a time that an LED assembly can't be determined without the visor being in place.
Title: Re: LED traffic signals
Post by: SSOWorld on December 17, 2009, 01:04:10 PM
The purpose of the hood can be two-fold.  it prevented sunlight from dimming the light - and it prevents cross-traffic from "cheating" (looking at the cross light rather than their light)
Title: Re: LED traffic signals
Post by: mightyace on December 17, 2009, 04:19:57 PM
Quote from: Master son on December 17, 2009, 01:04:10 PM
it prevents cross-traffic from "cheating" (looking at the cross light rather than their light)

Of course, that is not always effective at night as light will reflect off the hoods and other nearby objects.

IMHO Watching the other light to anticipate yours turning green is not "cheating."  However, I've stopped doing it for a more practical reason.  Too many people in Middle TN run the light as they turn red or just after they turn red, so starting as soon as you get the green is an invitation to get T-boned.  :ded:
Title: Re: LED traffic signals
Post by: Scott5114 on December 17, 2009, 04:49:54 PM
Of course, that would be their fault, so with luck in the insurance process you may get [Rich Fields] a brand new caaaaaaahhh! [/Rich Fields] ;)
Title: Re: LED traffic signals
Post by: mightyace on December 17, 2009, 04:59:57 PM
Quote from: Scott5114 on December 17, 2009, 04:49:54 PM
Of course, that would be their fault, so with luck in the insurance process you may get [Rich Fields] a brand new caaaaaaahhh! [/Rich Fields] ;)

At least my heirs will, anyway.  :sombrero:
Title: Re: LED traffic signals
Post by: agentsteel53 on December 17, 2009, 05:38:09 PM
Quote from: Master son on December 17, 2009, 01:04:10 PM
it prevents cross-traffic from "cheating" (looking at the cross light rather than their light)

what's wrong with cheating?  I for one really like to "cheat", as I drive a stick shift, and I can anticipate the green and get off the line a couple fractions of a second more efficiently if I use the cross-light turning red as my "put car back in gear and prepare to raise the clutch" indicator.
Title: Re: LED traffic signals
Post by: Ian on December 17, 2009, 06:37:46 PM
OT about LEDs. I found out that the intersection of NH 106 and NH 9 near Concord Heights, NH, was the first intersection in the nation to be equipped with green LED traffic signals! Next time I go their, I will be sure to snap some shots of those LEDs since the originals are still lit (well, they're LED's, so of course).
Title: Re: LED traffic signals
Post by: agentsteel53 on December 17, 2009, 06:39:44 PM
what year was this LED light installed?
Title: Re: LED traffic signals
Post by: Ian on December 17, 2009, 06:41:11 PM
Quote from: agentsteel53 on December 17, 2009, 06:39:44 PM
what year was this LED light installed?

According to Wikipedia, the exact date is May 17, 1996
Title: Re: LED traffic signals
Post by: Duke87 on December 17, 2009, 08:38:56 PM
Quote from: Master son on December 17, 2009, 01:04:10 PM
The purpose of the hood can be two-fold.  it prevented sunlight from dimming the light - and it prevents cross-traffic from "cheating" (looking at the cross light rather than their light)

Drivers taking a peek at the light in the other direction isn't an issue.
On the other hand, drivers seeing the other direction's green light and thinking it's theirs is, particularly at intersections where two streets meet at a significant angle and so the other lights are sort of facing you.
Title: Re: LED traffic signals
Post by: jjakucyk on December 18, 2009, 12:36:17 AM
Quote from: PennDOTFan on December 17, 2009, 06:37:46 PM
OT about LEDs. I found out that the intersection of NH 106 and NH 9 near Concord Heights, NH, was the first intersection in the nation to be equipped with green LED traffic signals! Next time I go their, I will be sure to snap some shots of those LEDs since the originals are still lit (well, they're LED's, so of course).

I wouldn't be so sure.  I've seen a handful of older (not sure how old, but probably late 90s or early 00s) LED signals in North Carolina and a few here in Ohio that are going bad.  Several of the individual elements have gone out, usually in some sort of strange pattern, with others flickering badly.  It's an odd thing to see, but I guess it illustrates how it's not the individual LEDs themselves, but the circuitry controlling them that eventually fails. 
Title: Re: LED traffic signals
Post by: Ian on December 18, 2009, 04:03:46 PM
Quote from: jjakucyk on December 18, 2009, 12:36:17 AM
Quote from: PennDOTFan on December 17, 2009, 06:37:46 PM
OT about LEDs. I found out that the intersection of NH 106 and NH 9 near Concord Heights, NH, was the first intersection in the nation to be equipped with green LED traffic signals! Next time I go their, I will be sure to snap some shots of those LEDs since the originals are still lit (well, they're LED's, so of course).

I wouldn't be so sure.  I've seen a handful of older (not sure how old, but probably late 90s or early 00s) LED signals in North Carolina and a few here in Ohio that are going bad.  Several of the individual elements have gone out, usually in some sort of strange pattern, with others flickering badly.  It's an odd thing to see, but I guess it illustrates how it's not the individual LEDs themselves, but the circuitry controlling them that eventually fails. 

Yeah, and if you go to Rhode Island, a lot of the LED signals there are burning out. Check out on photo of mine I took this past Spring:
http://picasaweb.google.com/Iansignal/RhodeIslandTrafficSignalsAndRoadSigns#5324332473914119986
Title: Re: LED traffic signals
Post by: jjakucyk on December 18, 2009, 04:07:24 PM
Yeah, those ones with the circular pattern are the only ones I've seen going bad though.  I don't know if it's simply a different manufacturer or a different technology altogether, but I've never seen any of the following more gridded LEDs go bad yet.

(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fhomepage.mac.com%2Fjjakucyk%2Fsignals3%2FDSC_4285.jpg&hash=d4bba7827f03afb23801944cd31e4c2abd139d09)
Title: Re: LED traffic signals
Post by: Truvelo on December 18, 2009, 04:12:52 PM
Are there any incandescent traffic lights remaining in the US? All the ones I've seen are LED.
Title: Re: LED traffic signals
Post by: agentsteel53 on December 18, 2009, 04:15:15 PM
Quote from: Truvelo on December 18, 2009, 04:12:52 PM
Are there any incandescent traffic lights remaining in the US? All the ones I've seen are LED.

there are plenty, but they tend to be along less important or older routes.
Title: Re: LED traffic signals
Post by: jjakucyk on December 18, 2009, 04:15:54 PM
Oh yes, I'd say the majority are still incandescent.  While most new ones are LED, many municipalities are in no hurry to change out their existing ones.
Title: Re: LED traffic signals
Post by: Truvelo on December 18, 2009, 04:26:21 PM
Perhaps it's just the areas I've been to have adopted LED's more than other areas. For what it's worth the state I've driven in most is PA.
Title: Re: LED traffic signals
Post by: Brandon on December 18, 2009, 04:49:35 PM
Quote from: Truvelo on December 18, 2009, 04:12:52 PM
Are there any incandescent traffic lights remaining in the US? All the ones I've seen are LED.

Plenty.  They are mostly on local (county, municipal) roads and streets, but there are still a fair number on state maintained highways.
Title: Re: LED traffic signals
Post by: roadfro on December 18, 2009, 06:18:04 PM
Quote from: jjakucyk on December 18, 2009, 04:15:54 PM
Oh yes, I'd say the majority are still incandescent.  While most new ones are LED, many municipalities are in no hurry to change out their existing ones.

Depends on the municipality. Examples from the Vegas area:

City of Las Vegas was very aggressive in changing to LEDs (first reds, then the greens and yellows as that technology developed) in the early 2000s--they were pursing the electricity savings. I'd venture to say that Las Vegas has few (if any) incandescents left in the city.

City of North Las Vegas was probably the first to start implementing all LEDs in new signal installations. However, they have not been very aggressive in retrofitting existing signals, and still has quite a few incandescents, especially in older areas of the city.

Clark County (controlling much of the unincorporated urban Vegas area) and City of Henderson were in between.  They specified LEDs at new installations, but were slower to start replacements, but I'd guess they are both over 80% LED by now.


It's also interesting to note that in many places where there had been incandescent bulbs, the colored lenses were often left in place. It was kinda difficult to tell if a signal had switched--the telltale sign being that green indication usually lost its bluish tint once the LEDs were installed.



Title: Re: LED traffic signals
Post by: Scott5114 on December 18, 2009, 09:45:08 PM
Oklahoma City still has a lot of them, especially in the more lower-middle and lower-class areas. The suburbs have a lot more LEDs.
Title: Re: LED traffic signals
Post by: deathtopumpkins on December 18, 2009, 11:56:39 PM
Here most lights are still incandescent. In fact my city recently installed new signals that used incandescent bulbs after the existing ones were torn apart in the November Nor'easter.
Title: Re: LED traffic signals
Post by: mightyace on December 19, 2009, 12:10:20 AM
It's hard for me to say which is more prevalent around here, though Franklin, TN surprised me by using incandescent bulbs on several new signals.

Maybe the city, literally, thinks it has money to burn as it's the county seat of Williamson County which is one of 20 richest counties in the country.

P.S. I live in Maury (pronounced Murry) County about two or three miles south of the Williamson County line.  (property taxes are much less then in Williamson County)
Title: Re: LED traffic signals
Post by: Scott5114 on December 19, 2009, 12:11:23 AM
Wait, Tennessee has traffic signals that have flaming cash as the lighting element? Can you get pictures?
Title: Re: LED traffic signals
Post by: SSOWorld on December 21, 2009, 06:43:28 AM
LEDs are "burning out" probably because the circuits they're built on are badly designed or installed.
Title: Re: LED traffic signals
Post by: Lukeisroads on July 27, 2022, 03:37:40 PM
This Thread seems like its dying shall we Bring it Back?
Title: Re: LED traffic signals
Post by: US 89 on July 27, 2022, 03:39:19 PM
Quote from: Lukeisroads on July 27, 2022, 03:37:40 PM
This Thread seems like its dying shall we Bring it Back?

No
Title: Re: LED traffic signals
Post by: Lukeisroads on July 27, 2022, 03:40:13 PM
Quote from: US 89 on July 27, 2022, 03:39:19 PM
Quote from: Lukeisroads on July 27, 2022, 03:37:40 PM
This Thread seems like its dying shall we Bring it Back?

No
Fair